The present invention relates to a device, hereafter apparatus, to adapt, hereafter fit, a hearing aid to the auditory needs of an individual with said hearing device applied.
Increasing the hearing-aid industry processes the audio signals digitally. At the near end of a process, a digital signal-processing unit transmits audio signals to an electrical/mechanical coupler of a hearing aid. The transfer function of the hearing aid between the acoustic/electric input transducer and the electric/mechanical output transducer is set up in such manner at the signal processing unit that the hearing aid shall extensively eliminate idiosyncratic hearing deficiencies.
It is probably obvious that such hearing aids can be optimally useful if—usually stepwise—first a coarse fitting is carried out and then, in situ, a fine one during which the hearing-aid transfer parameters are matched to idiosyncratic needs.
Typically coarse fitting is based on diagnostic data such as audiograms. At least part of the transfer parameters are fitted on the basis of such data in the hearing aid, or else the kind of hearing aid is selected first accordingly.
Then fine fitting is carried out in situ. Basically an individual to receive one or two hearing aids shall wear it (them) to be exposed to test auditory signals. Said individual is asked to report his responses to the test signals and fine fitting of parameters is then carried out accordingly.
It also follows clearly that manually fine-fitting the transfer parameters at the hearing aids while at the individual's ear is an impractical procedure if carried out manually, for instance by operating a potentiometer. Accordingly such hearing aids are equipped with an appropriate interface, namely a communication link to a fitting calculator, primarily to the communication system “computer to hearing aid”.
In the simplest case, which however is not operatively the optimal one, the individual verbally informs an expert, such as a hearing-aid acoustician, of his rating of the audio test signal. The acoustician, following appropriate conversion, feeds data into an input device, usually a keypad, to the fitting calculator. This calculator determines/computes setpoints of electronic units of the hearing aid, said setpoints being transmitted by said communication link from the fitting calculator to the hearing aid.
Such operations, being based on verbal communication of the individual's response to audio test signals and the conversion into quantified inputs to the fitting calculator, require unusually well trained technical personnel.
To eliminate this problem and to design the in-situ fitting procedure to be as short and as rational as possible regarding the said individual, individual responses already have been standardized and hence no longer are transferred through the hearing-aid specialist to the fitting calculator, but instead are transmitted directly. For that purpose input units with simple key functions are used, which allow the individual to rate the perceived audio test signals for instance on a given scale. This input unit communicates directly with the fitting calculator.
In increasing manner, digital hearing aids are being fitted according to perceived psycho-acoustic values, namely loudness. Reference is made in this regard to the European patent document 0 661 906 A which corresponds to the U.S. application Ser. No. 08/720,748 by this applicant. Illustratively these documents elucidate how the psycho-acoustic perceived value (loudness) can be rated according to a scale by an individual and how a calculator unit sets the hearing-aid transfer parameters caused by the response to stimulus for the specific, critical frequency bands of human hearing. This procedure is comprehensively discussed in the cited document and affects the present invention only in that it explains for instance how a fitting calculator determines transfer-function parameters based on the individual's rated statements of loudness.